SR 99 Update

Driver alert: SR 520 closure this weekend
Congestion is expected on I-5 and I-90 this weekend as construction crews close much of SR 520, including the floating bridge. All lanes in both directions and all ramps between Montlake Boulevard East and I-405 will be closed from 11 p.m. Friday, Sept. 16 to 5 a.m. Monday, Sept. 19. The section of SR 520 between Montlake Boulevard East and I-5 will remain open.

Drivers heading to the Mariners and Sounders games this weekend and the St. Demetrios Greek festival in the Montlake area should prepare for heavy traffic. To help ease congestion, WSDOT is shifting the express lane schedules on I-5 and I-90.

Paving the way toward the new SR 99
Next week, crews will start paving sections of the four-lane SR 99 construction bypass and the new off-ramp to South Atlantic Street. The bypass and ramp will open by 5 a.m. Monday, Oct. 31, following the nine-day closure of SR 99. You may wonder why we’re moving the southbound SR 99 off-ramp from South Royal Brougham Way to South Atlantic Street. The answer lies in the construction bypass (pdf), which will cut across the path of the existing off-ramp. The new ramp will exit on the west side of the bypass and then travel under the new SR 99 bridge.

Did you know?
You may have noticed the row of 20 metal pipes on the west side of the viaduct. The pipes are part of work to build two main supports for the South Atlantic Street overpass. Construction on the rest of the overpass will start next year. This new bridge will improve connections between the Port of Seattle and I-5 and I-90, allowing traffic and freight to bypass the railroad track when it’s in use.

Why are we building the supports now? Again the answer is the SR 99 construction bypass, which will go right by them. Once the bypass opens, there won’t be any room for big cranes and pile drivers except smack dab in the middle of the bypass. Doing the support work before the bypass opens means we avoid between six and nine weekend closures of SR 99.